JP2014021334A - Developer conveying device and developing device including the same, and image forming apparatus - Google Patents

Abstract

In a developer transport device including a developer transport member having a hollow shape, the possibility that the developer aggregates into a cylindrical shape in a hollow portion is reduced.
A developing device includes a first conveying screw and a second conveying screw in order to circulate and convey the developer. The first conveying screw 72 includes a first screw 721 and a first protrusion 721K. The first screw 721 has a hollow internal space and extends in a spiral shape along the developer conveyance direction. The first protrusion 721K protrudes from the inner surface of the first screw 721 toward the hollow internal space.
[Selection] Figure 3

Description

  The present invention relates to a developer conveying device, a developing device including the same, and an image forming apparatus.

  2. Description of the Related Art Conventionally, a developing device in which a stirring screw is mounted in a developing housing is known as a developer conveying device that conveys a developer. The stirring screw of the developing device includes a shaft portion and a spiral piece disposed around the shaft portion. In the developing housing, the agitating screw is driven to rotate, so that the developer is conveyed in a predetermined conveying direction.

  When the adhesive force of the developer increases with the deterioration of the developer, the developer may adhere to the shaft portion. When the developer adheres to the shaft portion, a virtual shaft thickening of the stirring screw occurs, and the conveying performance of the stirring screw decreases. In the technique described in Patent Document 1, in order to eliminate the shaft thickening of the stirring screw as described above, a stirring screw having a so-called hollow shape that does not include a shaft portion in the axial center portion of the stirring screw, It is disclosed.

JP 2004-307140 A

  In the stirring screw described in Patent Document 1, the developer transported through the hollow portion of the stirring screw sometimes aggregates in the developer housing. Such agglomeration of the developer becomes prominent when the high temperature environment or the developer deteriorates. In particular, the developer may agglomerate in a cylindrical shape inside a stirring screw having a hollow shape.

  The present invention has been made in view of the above problems, and in a developer conveying device including a developer conveying member having a hollow shape, the risk of the developer agglomerating in a cylindrical shape in a hollow portion is reduced. It is an object of the present invention to provide a developer conveying device capable of achieving the above, a developing device including the same, and an image forming apparatus.

  The developer transport device according to the present invention includes a housing having a pair of wall portions, a developer transport path extending between the pair of wall portions, and rotatably supported by the wall portion. A conveying member that conveys the developer from the wall portion toward the other wall portion, wherein a spiral piece that forms a spiral of one round is continuously provided in the developer conveying direction, and the spiral provided continuously A spiral member having a hollow interior space formed by a piece, a shaft portion disposed at both ends of the spiral member, rotatably supported by the wall portion, and serving as a rotation axis in rotation of the transport member; and the spiral And a protruding member that protrudes from the inner surface of the member toward the hollow internal space.

  When the temperature in the housing becomes high or when the developer deteriorates, the fluidity of the developer conveyed through the developer conveyance path may be reduced. In this case, the developer tends to be aggregated in a cylindrical shape inside the hollow of the spiral member. Even in such a case, according to this configuration, since the protruding portion that protrudes from the inner surface of the spiral member toward the inside of the hollow inner space is provided, the protruding portion causes the hollow member to enter the hollow interior of the spiral member. The developer lump that is placed is scraped. As a result, the possibility that the developer aggregates in a cylindrical shape in the hollow portion is reduced.

  Moreover, it is preferable that the said protrusion part is a rod-shaped protrusion and extends in the direction orthogonal to the said conveyance direction.

  According to this configuration, since the protruding portion protrudes into the developer block in a direction perpendicular to the developer transport direction, the developer block can be effectively scraped.

  A rib member that extends in the transport direction and bridges the adjacent spiral pieces of the spiral member; and is disposed to face the wall portion; and an end portion of the rib member in the transport direction; It is preferable to further include a support member that continuously connects the shaft portion.

  According to this configuration, the spiral portion of the spiral member is stably supported by the rib member.

  Further, the protruding portion protrudes between a first bridging position between the spiral piece and the rib member and a second bridging position on the downstream side in the spiral direction following the first bridging position. It is preferable.

  If the protrusion is formed at the connecting position between the spiral piece and the rib member, the flow of the developer is stagnated, and the developer tends to become a starting point for adhering to the protrusion or the spiral piece. According to this configuration, the protrusion is formed so as to avoid the connecting position between the spiral piece and the rib member, so that the possibility that the developer adheres to the protrusion or the spiral piece is reduced.

  Moreover, it is preferable to further provide an auxiliary protrusion protruding from the inner surface of the rib member to the hollow internal space.

  According to this configuration, as a result of the developer being scraped by the auxiliary protrusion, the effect of preventing the developer from aggregating in a cylindrical shape is increased.

  The auxiliary protrusion includes a first bridging portion between the first spiral piece and the rib member, and a second bridging portion between the second spiral piece and the rib member on the downstream side in the spiral direction of the first spiral piece. It is preferable that it is formed on the inner surface of the rib member at a position separated from the first and second bridging positions by a predetermined distance or more.

  If the auxiliary protrusion is formed in the vicinity of the connection position between the spiral piece and the rib member, the flow of the developer is stagnated, and the developer tends to become a starting point for adhering to the auxiliary protrusion or the spiral piece. According to this configuration, since the auxiliary protrusion is formed on the inner surface of the rib member at a position separated from the bridging position between the spiral piece and the rib member by a predetermined distance or more, the developer is provided with the auxiliary protrusion or the spiral piece. The risk of adhering to the surface is reduced.

  Moreover, it is preferable that the said auxiliary | assistant protrusion is formed in the inner surface of the said rib member in the approximate center position of the said 1st bridge part and the said 2nd bridge part.

  According to this configuration, the auxiliary protrusion can be formed at a position farthest from the connection location where the spiral piece and the rib member are connected.

  Moreover, it is preferable that a plurality of the rib members are arranged at intervals in the circumferential direction.

  According to this configuration, the effect of preventing the developer from aggregating into a cylindrical shape increases as a result of the developer being cut at a plurality of locations by the plurality of rod-shaped members.

  In addition, a developing device according to the present invention includes a developing roller that is rotatably supported by the housing and carries the developer, and the developer conveying device described above that conveys the developer to the developing roller. .

  According to this configuration, the developer conveying device reduces the possibility that the developer aggregates in a cylindrical shape inside the hollow of the spiral member. As a result, the possibility that the developer aggregates inside the developing device is reduced. Furthermore, toner aggregates are prevented from adhering to the developing roller.

  The developer is preferably made of a one-component toner.

  According to this configuration, even if the developer used in the developing device is a one-component toner, the possibility that the toner aggregates in a cylindrical shape in the hollow inside of the spiral member is reduced. In the case of a two-component developer from a carrier and a toner, the carrier collides with the toner as the developer is agitated. Therefore, toner aggregation is less likely to occur compared to a one-component toner. On the other hand, with the one-component toner, the above-described action is unlikely to occur, and the toner is likely to aggregate in a cylindrical shape inside the hollow of the spiral member. Even in such a case, according to the above configuration, aggregation of the one-component toner is effectively suppressed by the inner wall portion of the spiral member.

  In addition, an image forming apparatus according to the present invention includes an image carrier on which an electrostatic latent image is formed on a peripheral surface and disposed to face the developing roller, and the developing device described above.

  According to this configuration, the developer conveying device reduces the possibility that the developer aggregates in a cylindrical shape inside the hollow of the spiral member. As a result, the possibility that the developer aggregates into a cylindrical shape in the hollow interior is reduced. Therefore, the risk that the developer aggregates inside the developing device is reduced. Furthermore, toner aggregates are prevented from adhering to the developing roller. For this reason, toner aggregates are supplied to the image carrier and image quality defects are effectively prevented from occurring.

  According to the present invention, in the developer transport device including the developer transport member having a hollow shape, the developing device including the developer transport device, and the image forming apparatus, the possibility that the developer aggregates into a cylindrical shape in the hollow portion is reduced. it can.

1 is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view showing an internal structure of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view showing an internal structure of a developing device according to an embodiment of the present invention. It is a front view of the conveyance screw concerning one embodiment of the present invention. It is a perspective view of the conveyance screw which concerns on one Embodiment of this invention. It is a top view of the conveyance screw concerning one embodiment of the present invention. It is a perspective view of the conveyance screw which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an appearance of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a side sectional view showing the internal structure of the image forming apparatus 1 according to the embodiment of the present invention. Here, a monochrome printer is illustrated as the image forming apparatus 1, but the image forming apparatus may be a copying machine, a facsimile machine, or a multifunction machine having these functions, and an image forming apparatus that forms a color image. It may be.

  The image forming apparatus 1 includes a main body housing 10 having a substantially rectangular parallelepiped housing structure, and a paper feeding unit 20, an image forming unit 30, a fixing unit 40, and a toner container 50 housed in the main body housing 10. .

  A front cover 11 is provided on the front side of the main body housing 10, and a rear cover 12 is provided on the rear side. When the front cover 11 is opened, the toner container 50 is exposed to the front side. Thereby, the user can take out the toner container 50 from the front side of the main body housing 10 when the toner runs out. The rear cover 12 is a cover that is opened at the time of sheet jam or maintenance. The units of the image forming unit 30 and the fixing unit 40 can be taken out from the rear side of the main body housing 10 by opening the rear cover 12. Further, on the side surface of the main body housing 10, a left cover 12L (FIG. 1) and a right cover 12R (not shown in FIG. 1) opposite to the left cover 12L extend in the vertical direction. It is arranged. An intake port 12La for taking in air into the main body housing 10 is disposed at the front portion of the left cover 12L. Further, on the upper surface of the main body housing 10, a paper discharge unit 13 for discharging the sheet after image formation is provided. Various devices for executing image formation are installed in an internal space S (FIG. 2) defined by the front cover 11, the rear cover 12, the left cover 12L, the right cover 12R, and the paper discharge unit 13. The

  The paper feed unit 20 includes a paper feed cassette 21 that accommodates sheets to be subjected to image forming processing (FIG. 2). A part of the sheet feeding cassette 21 protrudes further forward from the front surface of the main body housing 10. An upper surface of a portion of the sheet cassette 21 accommodated in the main body housing 10 is covered with a sheet cassette top plate 21U. The sheet feeding cassette 21 is provided with a sheet accommodating space for accommodating the bundle of sheets, a lift plate for lifting the bundle of sheets for feeding. A sheet feeding portion 21 </ b> A is provided at an upper portion on the rear end side of the sheet feeding cassette 21. The sheet feeding unit 21A is provided with a sheet feeding roller 21B for feeding the uppermost sheet of the sheet bundle in the sheet feeding cassette 21 one by one.

  The image forming unit 30 performs an image forming process for forming a toner image on a sheet fed from the paper feeding unit 20. The image forming unit 30 includes a photosensitive drum 31 (image carrier), a charging device 32, an exposure device (not shown in FIG. 2), a developing device 70, and a transfer device disposed around the photosensitive drum 31. A roller 34 and a cleaning device 35. The image forming unit 30 is disposed between the left cover 12L and the right cover 12R.

  The photosensitive drum 31 includes a rotation shaft (not shown) and a cylindrical surface that rotates around the rotation shaft. An electrostatic latent image is formed on the cylindrical surface, and a toner image corresponding to the electrostatic latent image is carried on the cylindrical surface. As the photosensitive drum 31, a photosensitive drum using an amorphous silicon (a-Si) material can be used.

  The charging device 32 uniformly charges the surface of the photosensitive drum 31, and includes a charging roller that contacts the photosensitive drum 31.

  The cleaning device 35 has a cleaning blade (not shown), cleans the toner attached to the cylindrical surface of the photosensitive drum 31 after the toner image is transferred, and conveys the toner to a collecting device (not shown). Further, the photosensitive drum 31, the charging device 32, and the cleaning device 35 are integrally configured as a drum unit (not shown).

  The exposure apparatus has a laser light source and optical equipment such as a mirror and a lens, and irradiates the peripheral surface of the photosensitive drum 31 with light modulated based on image data given from an external device such as a personal computer. An electrostatic latent image is formed. The developing device 70 supplies toner to the peripheral surface of the photosensitive drum 31 in order to develop the electrostatic latent image on the photosensitive drum 31 to form a toner image. The developing device 70 includes a developing roller 71 that carries toner to be supplied to the photosensitive drum 31, a first conveying screw 72 and a second conveying screw 73 that circulate and convey the developer inside a developing housing (not shown). including. The developing device 70 will be described in detail later.

  The transfer roller 34 is a roller for transferring a toner image formed on the cylindrical surface of the photosensitive drum 31 onto a sheet. The transfer roller 34 is in contact with the cylindrical surface of the photoconductor drum 31 to form a transfer nip portion. The transfer roller 34 is given a transfer bias having a polarity opposite to that of the toner.

  The fixing unit 40 performs a fixing process for fixing the transferred toner image on the sheet. The fixing unit 40 includes a fixing roller 41 having a heating source therein, and a pressure roller 42 that is pressed against the fixing roller 41 and forms a fixing nip portion with the fixing roller 41. When the sheet on which the toner image has been transferred is passed through the fixing nip portion, the toner image is fixed on the sheet by heating by the fixing roller 41 and pressing by the pressure roller 42.

  The toner container 50 stores toner to be supplied to the developing device 70. The toner container 50 includes a container main body 51 serving as a main storage location of toner, a cylindrical portion 52 projecting from a lower portion on one side surface of the container main body 51, and a lid member 53 covering the other side surface of the container main body 51. And a rotating member 54 that is contained in the container and conveys toner. The toner stored in the toner container 50 is supplied into the developing device 70 from the toner discharge port 521 provided on the lower surface of the front end of the cylindrical portion 52 when the rotating member 54 is driven to rotate. Further, the container top plate 50 </ b> H covering the upper side of the toner container 50 is positioned below the paper discharge unit 13.

  In the main body housing 10, a main conveyance path 22F and a reverse conveyance path 22B are provided to convey the sheet. The main conveyance path 22 </ b> F passes through the image feeding unit 21 and the fixing unit 40 from the sheet feeding unit 21 </ b> A of the paper feeding unit 20, and the paper discharge port 14 provided to face the paper discharge unit 13 on the upper surface of the main body housing 10. It extends to. The reverse conveyance path 22B is a conveyance path for returning a sheet printed on one side to the upstream side of the image forming unit 30 in the main conveyance path 22F when performing duplex printing on the sheet.

  The main transport path 22F is extended so as to pass through a transfer nip portion formed by the photosensitive drum 31 and the transfer roller 34 from the lower side to the upper side. In addition, a registration roller pair 23 is disposed on the upstream side of the transfer nip portion of the main conveyance path 22F. After the sheet is temporarily stopped by the registration roller pair 23 and skew correction is performed, the sheet is sent out to the transfer nip portion at a predetermined timing for image transfer. A plurality of transport rollers for transporting the sheet are disposed at appropriate positions on the main transport path 22F and the reverse transport path 22B. For example, a pair of paper discharge rollers 24 is disposed in the vicinity of the paper discharge port 14.

  The reverse conveyance path 22 </ b> B is formed between the outer side surface of the reverse unit 25 and the inner surface of the rear cover 12 of the main body housing 10. Note that one roller of the transfer roller 34 and the registration roller pair 23 is mounted on the inner surface of the reversing unit 25. The rear cover 12 and the reversing unit 25 can be rotated about the axis of the fulcrum 121 provided at the lower end thereof. When a sheet jam occurs in the reverse conveyance path 22B, the rear cover 12 is opened. When a sheet jam occurs in the main conveyance path 22F, or when the unit of the photosensitive drum 31 and the developing device 70 are taken out, the reversing unit 25 is opened in addition to the rear cover 12.

<Detailed configuration of developing device>
Next, the configuration of the developing device 70 according to the present embodiment will be described in detail with reference to FIG. 3A is a cross-sectional view of the first conveying screw 72 and the second conveying screw 73 disposed in the developing device 70, and FIG. 3B is a plan view of the developing housing 70A of the developing device 70. is there. FIG. 3B shows a state in which the lid (not shown) of the developing housing 70A is removed.

  The developing device 70 includes a developing housing 70 </ b> A (housing) that defines an internal space of the developing device 70. The developing housing 70A includes a lid (not shown) that covers each roller accommodated therein from above, and a bottom that is connected to the lid and forms a lower surface of the developing housing 70A. In FIG. 3, the bottom side of the developing housing 70A appears. The developing housing 70A includes a first wall portion 70B and a second wall portion 70C that are a pair of wall portions.

  The developing housing 70A is provided with a developer storing portion 74 that is a cavity for storing a developer made of magnetic toner and can transport the developer while stirring. Further, in the developing housing 70A, there are a developing roller 71, a development regulating blade 75 (FIG. 2) disposed opposite to the developing roller 71, a first conveying screw 72 and a second conveying screw for stirring and conveying the developer. 73 is disposed.

  The developer storage section 74 includes two adjacent first and second transport sections 74a and 74b that extend in the longitudinal direction of the developing device 70 between the first wall section 70B and the second wall section 70C. Both include a developer conveyance path). The first transport unit 74a and the second transport unit 74b are partitioned from each other by a partition plate 701 that is formed integrally with the bottom of the developing housing 70A and extends in the longitudinal direction. Moreover, the 1st conveyance part 74a and the 2nd conveyance part 74b are mutually connected by the 1st communication part 704 and the 2nd communication part 705 in the both ends in a longitudinal direction (refer FIG. 3).

  The first conveying screw 72 (conveying member) and the second conveying screw 73 (conveying member) are accommodated in the first conveying unit 74a and the second conveying unit 74b, respectively, and are rotated around the axis to agitate the developer and Transport. That is, the first conveying screw 72 and the second conveying screw 73 are rotatably supported by the first wall portion 70B and the second wall portion 70C, and are directed from one of the first wall portion 70B and the second wall portion 70C to the other. Transport the developer. In FIG. 3, the first conveying screw 72 is rotationally driven in the direction of arrow D2. On the other hand, the second conveying screw 73 is rotationally driven in the direction of arrow D3. The first conveying screw 72 and the second conveying screw 73 are set so that the developer conveying directions are opposite to each other in the axial direction. As a result, the developer is circulated and conveyed between the first conveyance unit 74a and the second conveyance unit 74b as indicated by arrows Da and Db in FIG.

  The developing roller 71 is disposed along the longitudinal direction of the developing device 70. The developing roller 71 is disposed along the second conveying screw 73. The developing roller 71 is rotationally driven in the direction of arrow D1 in FIG. A fixed so-called magnet roll is arranged inside the developing roller 71. The magnet roll has a plurality of magnetic poles. Developer is supplied to the peripheral surface of the developing roller 71 from the second conveying screw 73. Then, the developer carried on the peripheral surface of the developing roller 71 is conveyed downstream in the rotation direction of the developing roller 71 as the developing roller 71 rotates.

  The development regulating blade 75 (FIG. 2) is disposed in the circumferential direction of the developing roller 71 on the downstream side in the rotation direction of the developing roller 71 from the region where the developing roller 71 and the second conveying screw 73 face each other. The development regulating blade 75 extends in the axial direction of the developing roller 71 at a lid (not shown) of the developing housing 70A. The development regulating blade 75 is a plate-like member whose tip is disposed at a predetermined distance from the peripheral surface of the developing roller 71. The developer carried on the developing roller 71 is layer regulated by the development regulating blade 75. The developer on the developing roller 71 whose layer is regulated by the development regulating blade 75 is conveyed to the opposite portion between the developing roller 71 and the photosensitive drum 31, and corresponds to the electrostatic latent image formed on the photosensitive drum 31. , And supplied to the cylindrical surface of the photosensitive drum 31.

  Next, with reference to FIG. 4 to FIG. 7 in addition to FIG. 3, the first conveying screw 72 and the second conveying screw 73 arranged in the developing device 70 according to this embodiment will be described in detail. FIG. 4 is a front view of the first conveying screw 72, and FIG. 6 is a plan view of the second conveying screw 73. 5 and 7 are perspective views of the first conveying screw 72 and the second conveying screw 73, respectively.

<About the first conveying screw 72>
The first conveying screw 72 (conveying member) will be described with reference to FIGS. 3, 4, and 5. As described above, the first transport screw 72 is disposed in the first transport unit 74a. The first conveying screw 72 includes an eleventh shaft portion 726, a twelfth shaft portion 727, an eleventh rib 722, a twelfth rib 723, an eleventh continuous piece 724, a twelfth continuous piece 725, One screw 721, a first seal 727S, a first protrusion 721K (protrusion), and a first auxiliary protrusion 721Ka (auxiliary protrusion).

  The eleventh shaft portion 726 (shaft portion) and the twelfth shaft portion 727 (shaft portion) are rotatably supported by the second wall portion 70C and the first wall portion 70B, respectively. The eleventh shaft portion 726 and the twelfth shaft portion 727 are shaft portions that serve as the rotation shaft of the first conveying screw 72. The eleventh shaft portion 726 and the twelfth shaft portion 727 rotatably support the first transport screw 72 on one end side and the other end side in the axial direction of the first transport screw 72, respectively. The eleventh shaft portion 726 includes a cylindrical bearing portion inside. A protrusion (not shown) protruding from the second wall portion 70C of the developing housing 70A toward the first transport portion 74a is inserted into the bearing portion of the eleventh shaft portion 726. Similarly, the twelfth shaft portion 727 includes a cylindrical bearing portion therein. Then, a protrusion (not shown) that protrudes from the first wall 70B of the developing housing 70A toward the first transport portion 74a is inserted into the bearing portion of the twelfth shaft portion 727. As a result, the first conveying screw 72 is rotatably supported by the developing housing 70A. At this time, in the axial direction of the first conveying screw 72, a virtual rotation shaft of the first conveying screw 72 is formed between the eleventh shaft portion 726 and the twelfth shaft portion 727.

  The eleventh rib 722 (rib member) and the twelfth rib 723 (rib member) are plate-like members respectively extending from one end side to the other end side of the first conveying screw 72. The eleventh rib 722 and the twelfth rib 723 are plate-like members having a predetermined width in the circumferential direction of the first conveying screw 72. The eleventh rib 722 and the twelfth rib 723 are arranged in parallel and facing each other around the rotation axis of the first conveying screw 72. In other words, the eleventh rib 722 and the twelfth rib 723 are arranged at an interval of 180 degrees in the circumferential direction of the first conveying screw 72. The eleventh rib 722 and the twelfth rib 723 are extended from the vicinity of the eleventh shaft portion 726 to the vicinity of the twelfth shaft portion 727 in the axial direction of the first conveying screw 72. The eleventh rib 722 and the twelfth rib 723 have a function of stirring the developer in the first transport unit 74a while supporting a first screw 721 described later.

  As the plurality of rib members, the eleventh rib 722 and the twelfth rib 723 are arranged at intervals in the circumferential direction, so that the first screw 721 is stably supported by the plurality of rib members. . As a result, the rotation of the first conveying screw 72 is stably maintained.

  The eleventh continuous piece 724 is disposed so as to face the second wall portion 70 </ b> C, and the end portions on one end side of the eleventh rib 722 and the twelfth rib 723 are continuously provided in the radial direction of the first conveying screw 72. . Further, the above-described eleventh shaft portion 726 protrudes from the central portion of the eleventh connecting piece 724 toward the outer side in the axial direction of the first conveying screw 72. In other words, the eleventh connecting piece 724 connects the end portions of the eleventh rib 722 and the twelfth rib 723 in the transport direction and the eleventh shaft portion 726. Similarly, the twelfth connecting piece 725 connects the end portions on the other end side of the eleventh rib 722 and the twelfth rib 723 in the radial direction of the first conveying screw 72. Further, the above-described twelfth shaft portion 727 protrudes from the center portion of the twelfth connecting piece 725 toward the outer side in the axial direction of the first conveying screw 72.

  The eleventh rib 722 includes an eleventh tip 722 </ b> A on the outer side in the axial direction of the first conveying screw 72 than the eleventh continuous piece 724. The eleventh tip portion 722A is formed by projecting one end of the eleventh rib 722 axially outward (toward the second wall portion 70C) from the eleventh connecting piece 724. The eleventh rib 722 includes an eleventh rear end 722 </ b> B outside the twelfth connecting piece 725 in the axial direction of the first conveying screw 72. The eleventh rear end portion 722B is formed by projecting the other end of the eleventh rib 722 outward in the axial direction from the twelfth connecting piece 725 (toward the first wall portion 70B).

  Similarly, the twelfth rib 723 includes a twelfth tip 723 </ b> A on the outer side in the axial direction of the first conveying screw 72 than the eleventh connecting piece 724. The twelfth tip portion 723 </ b> A is formed by projecting one end of the twelfth rib 723 outward in the axial direction from the eleventh connecting piece 724. The twelfth rib 723 includes a twelfth rear end portion 723 </ b> B outside the twelfth connecting piece 725 in the axial direction of the first conveying screw 72. The twelfth rear end 723 </ b> B is formed by projecting the other end of the twelfth rib 723 outward in the axial direction from the twelfth connecting piece 725.

  The first screw 721 (spiral member) extends in a spiral shape in the developer conveyance direction, and forms the outer peripheral edge of the first conveyance screw 72. That is, the first screw 721 is formed by connecting spiral pieces that form a spiral around the first screw 721 in the transport direction. The first screw 721 includes a hollow internal space formed by the spiral pieces connected to each other. In other words, the first screw 721 is disposed between the eleventh shaft portion 726 and the twelfth shaft portion 727 with a gap in the radial direction from the virtual rotation axis of the first conveying screw 72, and has a hollow interior. It is a spiral conveying member provided with a space. The eleventh rib 722 and the twelfth rib 723 described above bridge the adjacent spiral pieces of the first screw 721. In other words, the configuration of the first screw 721, the eleventh rib 722, and the twelfth rib 723 is composed of a plurality of the spiral pieces, and a plurality of the eleventh rib 722 and the twelfth rib 723 provide a plurality of these. As a result, a spiral first screw 721 having a hollow portion on the axial center side is formed. As shown in FIGS. 3B, 4, and 5, there are regions where the first screw 721 is not disposed at both axial ends of the eleventh rib 722 and the twelfth rib 723. .

  Referring to FIG. 4, the spiral portion of the first screw 721 includes a ridge portion 721 </ b> R that forms an outer peripheral edge that is the maximum diameter of the first screw 721 in a cross-sectional view including the rotation axis of the first conveying screw 72, and The ridgeline portion 721R is composed of a pair of inclined surfaces 721P and 721Q facing toward one end side and the other end side in the axial direction. The outer peripheral edge in the cross-sectional view may be, for example, a circular or elliptical curved shape, or may be another shape.

  Furthermore, for example, a plurality of plane portions that are continuously provided in the circumferential direction of the first conveying screw 72 are arranged inside the spiral portion of the first screw 721. That is, in the first screw 721, on the inner side (back side) of the ridge line portion 721R, the pair of slopes 721P and 721Q are continuously provided by the plane portion. The planar portion is arranged inside the ridge line portion 721R while being bent at a predetermined angle along the axial direction of the first conveying screw 72.

  In other words, referring to FIG. 3A, the first inner wall portion 721 </ b> S (inner wall portion) is disposed on the inner peripheral portion of the first screw 721. The first inner wall portion 721 </ b> S faces the hollow interior of the first screw 721, and a plurality of plane portions are formed continuously at a predetermined angle in the circumferential direction. The first inner wall portion 721S includes an eleventh inner wall surface 721A, a twelfth inner wall surface 721B, a thirteenth inner wall surface 721C, a fourteenth inner wall surface 721D, a fifteenth inner wall surface 721E, a sixteenth inner wall surface 721F, a seventeenth inner wall surface 721G, 18 inner wall surface 721H (both are flat portions). As shown in FIG. 3A, these form a substantially regular octagon in a cross-sectional view that intersects the axial direction of the first conveying screw 72. That is, these inner wall surfaces are continuously provided at a certain angle in the circumferential direction. The thirteenth inner wall surface 721C and the seventeenth inner wall surface 721G correspond to the inner surface portions of the twelfth rib 723 and the eleventh rib 722, respectively. That is, of the plate-like twelfth rib 723 and eleventh rib 722, the inner surface facing the hollow interior forms part of the plurality of inner wall surfaces of the first screw 721.

  The first inner wall portion 721S may be configured such that a plurality of plane portions are continuously provided at a predetermined angle. In this case, not all angles need to be constant in the connected portions. Further, the inner wall surface of the first screw 721 may be circular or elliptical in a cross-sectional view intersecting the axial direction of the first screw 721, and the shape thereof is not limited to a specific shape. .

  The first protruding portion 721K is a protruding portion that protrudes from the inner surface of the first inner wall portion 721S toward the inner side of the hollow inner space, for example, toward the axial center of the first screw 721. The first auxiliary protrusion 721Ka is a protrusion that protrudes from the inner surfaces of the eleventh rib 722 and the twelfth rib 723 toward the inner side of the hollow internal space, for example, toward the axial center of the first screw 721.

  The first protrusion 721K and the first auxiliary protrusion 721Ka have a length that does not reach the axial center of the first screw 721. Thereby, the conveyance of the developer is not hindered.

  The first protrusion 721K and the first auxiliary protrusion 721Ka are formed by, for example, integral molding with the first screw 721, the eleventh rib 722, and the twelfth rib 723. In the example shown in FIG. 3, the first protrusion 721 </ b> K is formed on the eleventh inner wall surface 721 </ b> A and the fifteenth inner wall surface 721 </ b> E of the first screw 721. A plurality of first auxiliary protrusions 721Ka are arranged on the inner surfaces of the eleventh rib 722 and the twelfth rib 723 with a predetermined interval.

  The first protrusion 721K includes a first bridging position of the first screw 721, the eleventh rib 722, and the twelfth rib 723, and a second bridging position downstream in the spiral direction following the first bridging position. It protrudes between. Thereby, the first protrusion 721 </ b> K is formed at a location other than the connection position between the first screw 721 and the eleventh rib 722 and the twelfth rib 723. That is, the first protrusion 721K is formed so as to avoid the thirteenth inner wall surface 721C and the seventeenth inner wall surface 721G of the first screw 721.

  The first auxiliary protrusion 721Ka includes a first bridging portion between an arbitrary first spiral piece included in the first screw 721 and the eleventh rib 722, and a second spiral piece downstream of the first spiral piece in the spiral direction. And the second bridging portion of the eleventh rib 722. In other words, the first auxiliary protrusion 721Ka is substantially the center of the adjacent connection position between the first screw 721 and the eleventh rib 722, that is, the seventeenth inner wall surface 721G and the seventeenth inner wall surface 721G in the spiral pieces adjacent to each other. It is formed at a substantially central position.

  Similarly, the first protrusion 721K formed on the twelfth rib 723 has a thirteenth inner wall surface 721C at the approximate center of the adjacent connection position between the first screw 721 and the twelfth rib 723, that is, the spiral pieces adjacent to each other. And the thirteenth inner wall surface 721C.

  The first seal 727 </ b> S is an annular elastic member disposed on the radially outer side of the twelfth shaft portion 727. The first seal 727S is in contact with the inner wall portion of the first wall portion 70B of the developing housing 70A in a state where the first screw 721 is attached to the developing housing 70A. As a result, the first seal 727S prevents the developer from aggregating between the twelfth shaft portion 727 and the inner wall portion of the first wall portion 70B as the first conveying screw 72 rotates.

  Further, the first screw 721 includes an eleventh protrusion 728 and a twelfth protrusion 729.

  The eleventh protrusion 728 is a wall that protrudes in the radial direction from the outer wall portion on the radially outer side of the eleventh rib 722 and the twelfth rib 723. The eleventh protrusion 728 protrudes to a height slightly inward from the outer peripheral edge of the first screw 721 in the radial direction of the first conveying screw 72. In addition, in the axial direction of the first conveying screw 72, the base end portion of the eleventh protrusion 728 is connected to one blade portion of the first screw 721. The other end of the eleventh protrusion 728 is disposed between the one blade portion and another blade portion disposed adjacent to one blade of the first screw 721. In other words, the eleventh protrusion 728 is the first screw toward the direction in which the first conveying screw 72 conveys the developer (arrow Da in FIG. 3 and arrow D42 in FIG. 4) in the first conveying portion 74a. 721 extends from one blade portion. At this time, the tip end portion in the extending direction of the eleventh projecting portion 728 is not connected to the other blade portion disposed adjacent to the one blade portion, and is substantially the central portion of the two blade portions. Placed in.

  Similarly, the twelfth protrusion 729 (FIG. 5) is a wall portion protruding in the radial direction from the outer wall portion on the radially outer side of the eleventh rib 722. The twelfth protrusion 729 is disposed with a predetermined length in the axial direction at the end of the eleventh rib 722 on the eleventh shaft 726 side. The axially outer end of the twelfth protrusion 729 is disposed flush with the axially outer end of the eleventh tip 722A.

<About the second conveying screw 73>
Next, the 2nd conveyance screw 73 is demonstrated with reference to FIG.3 and FIG.6, FIG.7. In addition, since the shape of the 2nd conveyance screw 73 is similar to the shape of the 1st conveyance screw 72, description of a common part with the 1st conveyance screw 72 is abbreviate | omitted, and mainly the difference with the 1st conveyance screw 72 Will be described in detail. As described above, the second transport screw 73 is disposed in the second transport unit 74b. The second conveying screw 73 includes a twenty-first shaft portion 736, a twenty-second shaft portion 737, a twenty-first rib 732, a twenty-second rib 733, a twenty-first connection piece 734, a twenty-second connection piece 735, and a paddle. 737P, a second screw 731, a second seal 737S, a second protrusion 731K (protrusion), and a second auxiliary protrusion 731Ka (auxiliary protrusion).

  The 21st shaft portion 736 and the 22nd shaft portion 737 correspond to the 11th shaft portion 726 and the 12th shaft portion 727 of the first conveying screw 72. The second conveying screw 73 is rotatably supported by the developing housing 70A by the twenty-first shaft portion 736 and the twenty-second shaft portion 737. At this time, in the axial direction of the second transport screw 73, a virtual rotation shaft of the second transport screw 73 is formed between the 21st shaft portion 736 and the 22nd shaft portion 737.

  The 21st rib 732 and the 22nd rib 733 correspond to the 11th rib 722 and the 12th rib 723 of the first conveying screw 72. The twenty-first connecting piece 734 and the twenty-second connecting piece 735 correspond to the eleventh connecting piece 724 and the twelfth connecting piece 725 of the first conveying screw 72. As shown in FIG. 6, the twenty-second connecting piece 735 is disposed at a predetermined interval on the inner side in the axial direction than the twenty-second shaft portion 737. The twenty-first rib 732 and the twenty-second rib 733 are also extended to a region at a predetermined interval on the inner side in the axial direction from the twenty-second shaft portion 737, and are connected to each other by a twenty-second connecting piece 735. .

  The twenty-first rib 732 includes a twenty-first tip 732 </ b> A on the outer side in the axial direction of the second conveying screw 73 than the twenty-first connecting piece 734. The twenty-first tip portion 732A is formed by projecting one end of the twenty-first rib 732 outward in the axial direction (toward the second wall portion 70C) from the twenty-first connecting piece 734. Similarly, the 22nd rib 733 includes a 22nd tip 733A on the outer side in the axial direction of the second conveying screw 73 than the 21st connecting piece 734. The twenty-second tip 733A is formed by projecting one end of the twenty-second rib 733 outward in the axial direction from the twenty-first connecting piece 734. The 21st rib 732 and the 22nd rib 733 of the second conveying screw 73 are extended to a portion intersecting with the 22nd connecting piece 735, and the 22nd connecting screw 72 is provided like the first conveying screw 72. It does not extend outward in the axial direction from the piece 735.

  The paddle 737 </ b> P is a plate-like member that is disposed on the outer side in the axial direction of the 22nd connecting piece 735. The paddle 737P extends from the rotation shaft of the second conveying screw 73 in the radial direction. In the present embodiment, the paddle 737 </ b> P protrudes in the circumferential direction of the second conveying screw 73 toward the direction in which the 21st rib 732 is disposed. A 22nd shaft portion 737 is connected to the axially outer portion of the paddle 737P. Further, a second seal 737S, which will be described later, is connected to the outer edge of the paddle 737P in the axial direction. The paddle 737P has a function of delivering the developer from the second conveyance unit 74b to the first conveyance unit 74a via the first communication unit 704.

  The second screw 731 corresponds to the first screw 721 of the first conveying screw 72. The shape of the second screw 731 in a sectional view including the axial direction of the first conveying screw 72 is the same as that of the first conveying screw 72.

  In particular, referring to FIG. 3A, a second inner wall portion 731 </ b> S is disposed on the inner peripheral portion of the second screw 731. The second inner wall portion 731S is formed by connecting a plurality of plane portions with a predetermined angle. The second inner wall portion 731S includes a twenty-first inner wall surface 731A, a twenty-second inner wall surface 731B, a twenty-third inner wall surface 731C, a twenty-fourth inner wall surface 731D, a twenty-fifth inner wall surface 731E, a twenty-sixth inner wall surface 731F, a twenty-seventh inner wall surface 731G, 28 inner wall surface 731H. As shown in FIG. 3A, these form a substantially regular octagon in a cross-sectional view intersecting the axial direction of the second conveying screw 73. The 24th inner wall surface 731D and the 28th inner wall surface 731H correspond to the inner surface portions of the plate-like 22nd rib 733 and 21st rib 732, respectively.

  Note that the second inner wall portion 731 </ b> S may be configured such that a plurality of plane portions are continuously provided at a predetermined angle. In this case, not all angles need to be constant in the connected portions. Further, the inner wall surface of the second conveying screw 73 may be circular or elliptical in a cross-sectional view intersecting the axial direction of the second conveying screw 73, and the shape thereof may be a specific shape. It is not limited.

  The second protrusion 731 </ b> K is formed in the same manner as the first protrusion 721 </ b> K in the first conveying screw 72.

  The second protruding portion 731K is a protruding portion that protrudes from the inner surface of the second inner wall portion 731S toward the inner side of the hollow inner space, for example, toward the axial center of the second screw 731. The second auxiliary protrusion 731Ka is a protrusion protruding from the inner surfaces of the 21st rib 732 and the 22nd rib 733 toward the inner side of the hollow internal space, for example, toward the axial center of the second screw 731.

  The second protrusion 731 </ b> K and the second auxiliary protrusion 731 </ b> Ka have a length that does not reach the axial center of the second screw 731. Thereby, the conveyance of the developer is not hindered.

  The second protrusion 731 </ b> K and the second auxiliary protrusion 731 </ b> Ka are formed by integral molding with, for example, the second screw 731, the 21st rib 732, and the 22nd rib 733. In the example shown in FIG. 3, the second protrusion 731 </ b> K is formed on the 21st inner wall surface 731 </ b> A and the 25th inner wall surface 731 </ b> E of the second screw 731. A plurality of second auxiliary projections 731Ka are arranged on the inner surfaces of the 21st rib 732 and the 22nd rib 733 with a predetermined interval.

  The second protrusion 731K includes a first bridging position of the second screw 731, the 21st rib 732, and the 22nd rib 733, and a second bridging position on the downstream side in the spiral direction following the first bridging position. It protrudes between. Accordingly, the second protrusion 731 </ b> K is formed at a location other than the connection position between the second screw 731 and the 21st rib 732 and the 22nd rib 733. That is, the second protrusion 731K is formed so as to avoid the 24th inner wall surface 731D and the 28th inner wall surface 731H of the second screw 731.

  The second auxiliary protrusion 731Ka includes a first bridging portion between an arbitrary first spiral piece included in the second screw 731 and the 21st rib 732, and a second spiral piece downstream of the first spiral piece in the spiral direction. And the 21st rib 732 and the second bridge portion. In other words, the first auxiliary protrusion 721Ka is formed between the 28th inner wall surface 731H and the 28th inner wall surface 731H in the spiral center adjacent to each other, that is, at the approximate center of the adjacent connection position of the second screw 731 and the 21st rib 732. It is formed at a substantially central position.

  Similarly, the second protrusion 731K formed on the 22nd rib 733 is substantially the center of the connection position between the second screw 731 and the 22nd rib 733, that is, the 24th inner wall surface 731D and the 24th inner wall surface 731D in the spiral pieces adjacent to each other. It is formed at a substantially central position with respect to the 24 inner wall surface 731D.

  The second seal 737 </ b> S is an annular elastic member disposed on the radially outer side of the 22nd shaft portion 737. The second seal 737S is in contact with the inner wall portion of the first wall portion 70B of the developing housing 70A in a state where the second conveying screw 73 is attached to the developing housing 70A. As a result, the second seal 737 </ b> S prevents the developer from aggregating between the 22nd shaft portion 737 and the inner wall portion of the first wall portion 70 </ b> B as the second conveying screw 73 rotates.

  Further, the second conveying screw 73 includes a 21st protrusion 738 and a 22nd protrusion 739. The 21st protrusion 738 corresponds to the 11th protrusion 728 of the first conveying screw 72.

  On the other hand, the twenty-second protrusions 739 are a pair of wall portions protruding in the radial direction from the outer wall portions on the radially outer side of the twenty-first rib 732 and the twenty-second rib 733. The twenty-second projecting portion 739 is arranged with a predetermined length in the axial direction at the end of the twenty-first rib portion 732 and the twenty-second rib portion 733 on the twenty-first shaft portion 736 side. The end portions on the axially outer side of the 21st tip portion 732A and the 22nd tip portion 733A protrude slightly outward in the axial direction from the end portion on the axially outer side of the 22nd protrusion portion 739.

<About the effect of the 1st projection part 721K, the 1st auxiliary projection 721Ka, the 2nd projection part 731K, and the 2nd auxiliary projection 731Ka>
Next, the effect of the 1st projection part 721K and the 1st auxiliary projection 721Ka of the 1st conveyance screw 72 concerning this embodiment is explained. The following functions and effects are the same for the second protrusion 731K and the second auxiliary protrusion 731Ka of the second conveying screw 73.

  As described above, the first screw 721 of the first transport screw 72 is formed of a hollow spiral transport member. In other words, the first conveying screw 72 does not have a shaft portion between the eleventh shaft portion 726 and the twelfth shaft portion 727. For this reason, when the developer in the developer reservoir 74 is deteriorated or when the environment around the developing device 70 becomes high temperature, the viscosity of the developer increases and the developer adheres to the shaft portion. It is prevented. When the developer having increased viscosity adheres to the shaft portion, the transport performance of the transport screw including the shaft portion is degraded. The first conveying screw 72 according to the present embodiment can solve such a problem by including the hollow shape described above.

  On the other hand, if the fluidity of the developer is reduced due to the high temperature environment or the deterioration of the developer, the developer tends to stay in the hollow inside of the first screw 721. As a result, the developer may agglomerate with a cylindrical shape having the inner wall portion of the first screw 721 as the maximum outer diameter.

  However, the 1st conveyance screw 72 is provided with the 1st projection part 721K and the 1st auxiliary projection 721Ka which protrude toward the inner side of internal hollow space. Therefore, even when the developer aggregates into a cylindrical shape inside the hollow of the first screw 721, the first protrusion 721K and the first auxiliary protrusion 721Ka rotate together with the first screw 721 so as to scrape the developer. . Accordingly, the aggregated developer is scraped by the first protrusion 721K and the first auxiliary protrusion 721Ka. As a result, the first protrusion 721 </ b> K and the first auxiliary protrusion 721 </ b> Ka can reduce the possibility that the developer aggregates in a cylindrical shape in the hollow portion of the first screw 721.

  Note that the first protrusion 721 </ b> K and the first auxiliary protrusion 721 </ b> Ka are not necessarily configured to rotate together with the first screw 721. Even when the first protrusions 721K and the first auxiliary protrusions 721Ka are held in a hollow state in a stationary state, the first protrusions 721K and the first auxiliary protrusions 721Ka are disposed so as to cross the traveling direction of the developer. Can be scraped to some extent.

  Aggregation of the developer as described above becomes significant in the case of a one-component developer. This is because in the case of a two-component developer composed of a toner and a carrier, the carrier has a function of suppressing toner aggregation. With a two-component developer from a carrier and a toner, the carrier collides with the toner as the developer is agitated, and toner aggregation is less likely to occur compared to a one-component toner. On the other hand, with the one-component toner, the above-described action is unlikely to occur, and the toner is easily aggregated in a cylindrical shape inside the hollow of the first screw 721. Even in such a case, the first protrusion 721K and the first auxiliary protrusion 721Ka effectively suppress the aggregation of the one-component toner.

  Further, by arranging a plurality of first protrusions 721K and first auxiliary protrusions 721Ka at a predetermined interval, the developer is prevented from aggregating into a cylindrical shape as a result of the developer being scraped at a plurality of locations. The effect is increased. The interval at which the first protrusion 721K and the first auxiliary protrusion 721Ka are arranged may not be constant. It may be arranged at random intervals, or may be arranged experimentally in advance at a place where the developer tends to aggregate. The first auxiliary protrusion 721Ka may not be provided. Further, the first protrusion 721K and the first auxiliary protrusion 721Ka may be one.

  By forming the first auxiliary protrusion 721Ka on the eleventh rib 722 and the twelfth rib 723 in addition to the first protrusion 721K, the effect of reducing the possibility that the developer aggregates in a cylindrical shape increases.

  Further, if the first protrusion 721K is formed at or near the connecting position of the first screw 721 and the eleventh rib 722 and the twelfth rib 723, the flow of the developer is stagnated, and the toner is in the first protrusion. 721K, the first screw 721, the eleventh rib 722, and the twelfth rib 723 tend to be the starting point.

  Therefore, the first protrusion 721K is formed so as to avoid a connection position between the first screw 721 (spiral piece) and the eleventh rib 722 and the twelfth rib 723. Further, in the eleventh rib 722, at the approximate center of the adjacent connection positions of the first screw 721 and the eleventh rib 722, that is, the position farthest from each connection position of the first screw 721 and the eleventh rib 722. A first auxiliary protrusion 721Ka is formed. Further, in the twelfth rib 723, at the approximate center of the adjacent connecting positions of the first screw 721 and the twelfth rib 723, that is, at the position farthest from each connecting position of the first screw 721 and the twelfth rib 723. A first auxiliary protrusion 721Ka is formed.

  As a result, the toner adheres to the first protrusion 721K, the first screw 721, the eleventh rib 722, and the twelfth rib 723 due to the arrangement position of the first protrusion 721K and the first auxiliary protrusion 721Ka. The risk of doing so is reduced.

  The first auxiliary protrusion 721Ka only needs to be separated from the connection position between the first screw 721 and the eleventh rib 722 and the twelfth rib 723 by a predetermined distance or more. In the example formed in the approximate center of the adjacent connection position of the 1st screw 721 and the 11th rib 722 in 722, and the approximate connection position of the 12th rib 723 adjacent to the 1st screw 721 and the 12th rib 723. Not exclusively. A suitable separation distance can be appropriately determined experimentally, for example.

<About the effect of the 1st inner wall part 721S and the 2nd inner wall part 731S>
Next, the effect of the 1st inner wall part 721S of the 1st conveyance screw 72 concerning this embodiment is explained. In addition, the following effects are the same also about the 2nd inner wall part 731S of the 2nd conveyance screw 73. FIG.

  When the inner wall of the first screw 721 is formed of a continuous curved surface in the circumferential direction, the developer disposed on the inner side of the inner wall is more easily aggregated into a cylindrical shape. On the other hand, as described above, the first conveying screw 72 according to the present embodiment includes the first inner wall portion 721S. That is, the first inner wall portion 721S is formed by connecting a plurality of plane portions at a predetermined angle. As shown in FIG. 3A, the first inner wall portion 721 </ b> S forms a substantially regular octagon in a cross-sectional view that intersects the axial direction of the first conveying screw 72.

  According to the first inner wall portion 721 </ b> S as described above, a pressure that periodically varies in size is applied to the developer conveyed inside the first screw 721. That is, when the inner wall of the first screw 721 is viewed from the virtual rotation shaft portion of the first conveying screw 72 in the cross-sectional view, the locus of the inner wall of the first screw 721 is accompanied by the rotation of the first screw 721. However, it is fluctuate | varied between the surface part represented by 721 A of 11th inner wall surfaces, and the intersection part of these surfaces. The cross-sectional shape of the first inner wall portion 721S is not a circular shape with a uniform inner diameter but a different diameter. When rotated because of the different diameters, the developer lump disposed inside the hollow of the first screw 721 is easily broken. As a result, even when the developer fluidity is lowered, the first inner wall portion 721S has a function of breaking the toner inside the first screw 721. Further, a pressure that periodically varies in size is applied to the developer disposed inside the first screw 721. As a result, even when the developer fluidity is lowered, the first inner wall portion 721S has a function of breaking the toner inside the first screw 721. For this reason, as described above, the developer is prevented from aggregating in a cylindrical shape inside the first screw 721. In the second inner wall portion 731 </ b> S of the second conveying screw 73, the same effect is exhibited. The cross-sectional shapes of the first inner wall portion 721S and the second inner wall portion 731S are not limited to a substantially regular octagon. In the inner wall portion of the first screw 721 or the second screw 731, a plurality of plane portions are continuously provided at a predetermined angle in the circumferential direction, so that the same effect as described above is exhibited.

  Further, in the above-described embodiment, in the image forming apparatus 1 including the developing device 70, the developer is prevented from aggregating in a cylindrical shape inside the hollow of the first screw 721. This prevents toner aggregates from adhering to the developing roller 71. Therefore, toner agglomerates are supplied to the photosensitive drum 31 to effectively prevent image quality defects.

  As described above, the developing device 70 and the image forming apparatus 1 including the developing device 70 according to the embodiment of the present invention have been described. However, the present invention is not limited thereto, and for example, the following modified embodiment can be taken. it can.

  (1) Although the above embodiment has been described using the inside of the developing device 70 as the developer conveying device, the present invention is not limited to this. As the developer conveying device including the first conveying screw 72 or the second conveying screw 73, a toner container, a toner cartridge, a waste toner conveying device, or the like may be applied. Even in this case, the developer is prevented from being aggregated in a cylindrical shape in the hollow inside of the first screw 721 or the second screw 731.

  (2) In the above-described embodiment, the first conveyance screw 72 and the second conveyance screw 73 have been described as being supported by the developing housing 70A at both ends in the axial direction. It is not limited. The first conveying screw 72 and the second conveying screw 73 may be supported by the developing housing 70A at one end in the axial direction.

  (3) In the above embodiment, the configuration including the eleventh rib 722, the twelfth rib 723, the twenty-first rib 732, and the twenty-second rib 733 is shown, but the present invention is not limited to this. The eleventh rib 722, the twelfth rib 723, the twenty-first rib 732, and the twenty-second rib 733 may not be provided with all or a part thereof. For example, by configuring the first screw 721 and the second screw 731 with a material having high strength such as metal, all of the eleventh rib 722, the twelfth rib 723, the twenty-first rib 732, and the twenty-second rib 733, or It is good also as a structure which does not have one part.

  (4) In the above embodiment, the twelfth tip 723A, the twelfth rear end 723B, the twenty-second tip 733A, the twenty-second rear end 733B, the eleventh projection 728, the twelfth projection 729, and the twenty-first projection Although the configuration including the portion 738 and the twenty-second protrusion 739 is shown, the present invention is not limited to this. The twelfth tip portion 723A, the twelfth rear end portion 723B, the twenty-second tip portion 733A, the twenty-second rear end portion 733B, the eleventh protrusion portion 728, the twelfth protrusion portion 729, the twenty-first protrusion portion 738, and the twenty-second protrusion portion 739. It is good also as a structure which is not provided with all or one part.

  (5) In the above embodiment, the configuration in which the first auxiliary protrusion 721Ka is disposed on the eleventh rib 722 and the twelfth rib 723 is shown, but the present invention is not limited to this. The first auxiliary protrusion 721Ka may be disposed on any one of the eleventh rib 722 and the twelfth rib 723. Similarly, the configuration in which the second auxiliary protrusion 731Ka is disposed on the 21st rib 732 and the 22nd rib 733 is shown, but the present invention is not limited to this. What is necessary is just to arrange | position 2nd auxiliary protrusion 731Ka in any one of the 21st rib 732 and the 22nd rib 733. Further, the first auxiliary protrusion 721Ka and / or the second auxiliary protrusion 731Ka may not be provided.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 30 Image forming part 70 Development apparatus (developer conveyance apparatus)
70A Development housing (housing)
70B 1st wall part (wall part)
70C second wall (wall)
701 Partition plate 704 First communicating portion 705 Second communicating portion 71 Developing roller 72 First conveying screw (conveying member)
721 First screw (spiral member)
721K first protrusion (protrusion)
721Ka First auxiliary protrusion (auxiliary protrusion)
721S 1st inner wall part 722 11th rib (rib member)
723 12th rib (rib member)
724 11th connecting piece 725 12th connecting piece 726 11th shaft part (shaft part)
727 12th Shaft (Shaft)
73 Second conveying screw (conveying member)
731 Second screw (spiral member)
731K Second protrusion (protrusion)
731Ka Second auxiliary protrusion (auxiliary protrusion)
731S 2nd inner wall part 732 21st rib (rib member)
733 22nd rib (rib member)
734 21st connecting piece 735 22nd connecting piece 736 21st shaft portion 737 22nd shaft portion 737S second seal 737P paddle 74 developer storage portion 74a first transport portion 74b second transport portion 75 development regulating blade

Claims (11)

A housing with a pair of walls,
A developer conveying path extending between the pair of walls,
A conveying member that is rotatably supported by the wall and conveys the developer from one wall to the other wall;
A spiral member having a hollow inner space formed by a spiral piece that forms a spiral of the circumference and is continuously provided in the transport direction of the developer;
A shaft portion that is disposed at both ends of the spiral member, is rotatably supported by the wall portion, and serves as a rotation axis in the rotation of the transport member;
A protrusion protruding from the inner surface of the spiral member toward the hollow internal space;
A developer conveying device. The developer conveyance device according to claim 1, wherein the protrusion is a rod-shaped protrusion and extends in a direction orthogonal to the conveyance direction. A rib member extending in the transport direction and bridging the adjacent spiral pieces of the spiral member;
The developer conveying device according to claim 1, further comprising: a support member that is disposed to face the wall portion and connects the end portion of the rib member in the conveying direction and the shaft portion. The projecting portion is projected between a first bridging position between the spiral piece and the rib member and a second bridging position on the downstream side in the spiral direction following the first bridging position. 3. The developer conveying device according to 3. The developer conveying device according to claim 3, further comprising an auxiliary protrusion protruding from the inner surface of the rib member into the hollow internal space. The auxiliary protrusion is
Between the first bridging portion between the first spiral piece and the rib member, and the second bridging portion between the second spiral piece and the rib member on the downstream side in the spiral direction of the first spiral piece, The developer conveying device according to claim 5, wherein the developer conveying device is formed on an inner surface of the rib member at a position separated from the first and second bridging positions by a predetermined distance or more. The auxiliary protrusion is
The developer conveying device according to claim 6, wherein the developer conveying device is formed on an inner surface of the rib member at a substantially central position between the first bridging portion and the second bridging portion. The developer conveying device according to claim 3, wherein a plurality of the rib members are arranged at intervals in the circumferential direction. A developing roller that is rotatably supported by the housing and carries the developer;
The developer conveying device according to any one of claims 1 to 8, wherein the developer is conveyed to the developing roller.
A developing device comprising:   The developing device according to claim 9, wherein the developer is made of one-component toner. An electrostatic latent image is formed on the peripheral surface, and an image carrier disposed to face the developing roller;
An image forming apparatus comprising: the developing device according to claim 9.

Images